Fan impeller



June 1942- v Q M. H. FRISBIE 2,285,428

FAN IMPELLER Filed June 8, 1939 2 Sheets-Sheet l JNVENTOR BY mbw ATTORNEY June 9, 1942.

M. H. FRISBIE FAN IMPELLER 2 Sheets-Sheet 2 Filed June 8, 1959 INVENTOR.

ATTORNEYS.

Patented June 9, 1942 FAN IMPELLER Marshall H. Frisbie, Hamden, Comm, assignor to The A. 0. Gilbert Company, New Haven, Conn., a corporation of Maryland Application June 8, 1939, Serial No. 277,984

9 Claims.

This invention relates to air impellers adapted to be mounted directly upon the shaft of a small motor as in fans for use in the household and oilice, in automobile, and telephone booth interiors and other restricted places requiring air circulation.

One object of the invention is the provision of an impeller of unusually light weight and extreme simplicity of construction which at the same time shall be silent in operation, attractive in appearance, and virtually proof against permanent deformation of its designed blade contours by any of the common accidental causes of such deformation.

A contributory object is to provide means for assembling a nose cap with the central portion of a multiple blade sheet so as to substantially reinforce and stiffen the latter and in such manner that these parts may be separated and used over again or may be interchanged if desired.

A further object is to warp or distort the air fanning blade sheet portions which are not directly contacted by the nose cap into such air fanning surface contours that these blade portions of the sheet shall have uninterrupted surface smoothness and yet possess a greater ability to withstand forces tending to cause their deformation or collapse when the blade sheet itself is made of very thin or flexible material than would otherwise be the case. Thus rubber and other safety materials as well as the more pliable or resilient sheet metals or combinations of both may be employed as the material or materials of the blade sheet. Features of the blade outlines and surface contours apart from combinations which include the nose cap are not claimed herein but are claimed in my copending application divisional herefrom, Serial No. 404,585, filed July 30, 1941.

A still further object is to dispose the warped blade portions of the sheet on opposite sides of the plane of the central portions of the blade sheet in order to obtain the further strengthening influences of uniform distribution of weight along the whole axial extent of the blade sheet.

These and other objects of the improvements will become apparent from the following description of typical constructions in which the invention may be embodied, said description having reference to the accompanying drawings, where- Fig. 1 is a front view of a fan impeller embodying the invention,

Fig. 2 is an edgewise view of the impeller looking from the right at Fig. 1.

Fig. 3 is a fragmentary view of the rear of the impeller drawn on an enlarged scale, the blade sheet being partially broken away.

Fig. 4 is a view taken in section on the plane 4-4 in Fig. 3.

Fig. 5 is a perspective view of the nose cap before assemblage with the blade sheet.

Figs. 6, 7, 8 and 9 are further enlarged views taken in section respectively on the planes 6-6, l-'|, 8-8 and 99 in Fig. 1, looking in the direction of the arrows.

Fig. 10 is a fragmentary view of a modified form of the improvements otherwise similar to Fig. 3.

Figs. 11, 12, 13 and 14 are enlarged views taken in section respectively on the planes l|--l I, l2-

l2, l3-l3 and "-4 looking in the direction of the arrows in Fig. 10.

In impeller constructions involving a decorative nose cap for covering and concealing the end of the motor shaft or the true mounting hub of the impeller and designed for assemblage with a sheet of material forming fan blades it heretofore has been considered necessary to rib the sheet material with annular or radial grooves or to form sunken panels in the blade sheet itself, or to make use of solid and weighty hublike bodies for stiffening the central disc-like portion of the blade sheet sufllciently to sustain the blades in action. As such expedients are a source of noise and inefficiency beside adding to the cost of manufacture, it is desirable and particularly so in the smaller and low cost types of fan impellers, to eliminate these and all other dispensable parts and manufacturing operators. This is accomplished by the constructions chosen herein to illustrate the present implements.

The multiple blade sheet of the improved impeller as a whole is designated as I in Figs. 1 to 6 inclusive. It consists of a central flator planar disc-like portion or web ll, whose perimeter may be considered as falling on the circumferential line l2, together with the blade portions l6 outstanding therefrom. The direction of rotation is indicated by the curved arrow in Figs. 1 and 10. This disc-like portion web is centrally apertured to receive the usual hub l3 made fast thereto by peaning over at M its inwardly projecting nipple and contains the threaded hole IE to receive a set screw, not shown, by which hub l3 may be secured on the usual motor shaft, not shown. For imparting in fanning pitch the root portion of each blade which flanks and is outwardly contiguous to the perimeter l2 of the disc-like portion II, is

warped and may be twisted to impart to the blade portion l6 of the sheet In one offset I 9 which positions the air entering nose I! of the blade on the rear side of the plane of the disclike portion II and an opposite ofiset which positions the trailing end l8 of the blade on the forward side of the plane of said disc-like portion as shown in Fig. 2. At a point circumferentially between these rearward and forward offsets l9 and 20, the blade I 6 forms a smooth radial outward continuation of the disc-like portion II as shown in Fig. 8.

The offsets I9 and 20 are confined to approximately the shaded areas so designated in- Figs. 1 and 3 and merge into the flat web II as well as into the general or all-over conformation of the air impelling or front face. of the blade which in accordance with the principles taught in the U. S. Patent No. 2,022,417 granted to A. C. Gilbert et a1. preferably forms a tapered trough whose surface contains straight lines, roughly represented by the shade lines appearing in Fig. 1, and which are characterized by converging as they near the axis of impeller rotation. A trough as described may be said to be traversed by to the central disc-like portion ll, combined with the offsets I9 and 20 serve cooperatively to produce a maximum resistance of the blade to forces tending to distort its shape. Such blade even if made of unreinforced flexible resilient sheet rubber in it radially outward portions will have the strength to remain upright or sturdily outstanding without any appreciable degree of distortion or collapse either when stationary or when being rotated at high speed, its cone-like curvature having the peculiar quality of imparting this stand-up strength. Or in fans embodying a multiple blade sheet of the shape and contours above described, the material of the sheet may be metal of more than ordinary thinness, lightness and pliancy and for the same reasons possess the stand-up strength of a thicker or stiffer metal otherwise formed.

To further the above ends it is the plan of these. improvements to reinforce the central planar disc-like portion by applying thereagainst a nose cap 22 which may be hollow for lightness and made of thin drawn sheet metal or any other low cost material and for its purposes of reinforcing the blade sheet need be fastened only to the blade sheet, itself. For conveniently fastening this nose cap in one form of the invention, the latter is provided with tangs 23 formed by rearward extensions of its walls which elsewhere terminate in the planar edge or face 24. Tangs 23 are wide enough to snugly fill the circumferential extent of spaces 25 between adjacent edges of neighboring blades along the perimeter line l2 so that when these tangs extend through the said spaces respectively, the nose cap is rotatively interlocked with the blade sheet. The tangs are then bent radially inward over and against the rear surface of the blade sheet as shown in Figs. 3, 4 and 6 so that they draw the planar face or edge 24 of the nose cap 22 firmly against the front surface of the disc-like portion II at its perimeter thereby reinforcing and making this disc-like portion rigid to all intents and purposes by preventing its distortion in any part away from its designed plane of rotation. This manner of assembling the nose cap with the blade sheet also causes the nose cap to look more like an integral part of the whole impeller due to the fact that the-blade offset 20 closely overhangs the nose cap while the'blade offset l9 merges into and forms in appearance a rearward con- .tinuation of the outer wall of the nose cap.

In Figs. 10 to 14, inclusive, an alternative location for the tangs 23' relative to the blade sheet is shown, wherein apertures 26 are pierced in the disc-like portion of the blade sheet at its perimeter. Each aperture is preferably located relative to the root portion of the blade; at the point 2| which is circumferentially between the offsets I9 and 20. As tangs 23 snugly fit and fill the apertures 26 and are bent over in the same manner in Fig. 10 as in Figs. 3 and 4, a firm assemblage of the nose cap with the blade sheet results leaving exposed the spaces 25 between blade edges. As in the construction of Figs. 1 to 9, the nose cap of Figs. 10 to 14 may be removed and reassembled by straightening and rebending tangs 23.

In the relationship of theblades shown in Fig. 1 it will be observed that in this front view projection of the blades, each space 25 between blade edges extends radially outward in arcuate form and is of uniform width from the nose cap 22 to the narrow air entering nose I! of the blade It. This is a factor in the quietness and efll-' ing the principles of these improvements, and the appended claims are directed to and intended to cover all fair equivalents of the combinations, elements and features which fairly fall within the meaning of their terms.

The following is claimed:

1. In a fan, an air impeller including in combination, a multiple blade sheet composed of a central substantially fiat disc-like web with at least two air fanning blades comprising continuations of said web outstanding radially from the perimeter thereof said blades being warped to impart air fanning pitch to the blade and said web merging into said warped blades at the root and being the only portion of said blade sheet connecting said multiple blades, and a nose cap for preventing distortion of said web from a true plane thereby to assist in holding said blades in fixed mutual relationship said nose cap terminating in edges occupying said plane and abutting against the surface of said web at said perimeter of the latter closely adjacent said warped root portions of the blades.

2. In a fan, an air impeller including in combination, a multiple blade sheet composed of a central substantially fiat disc-like web with at least two air fanning blades comprising continuations of said web outstanding radially from the perimeter thereof said blades being twisted in their root portions contiguous to said perimeter in a manner to produce offsets in the leading end and trailing end of each blade on respectively opposite sides of the plane of said web and said web merging into said twisted root portions and being the only portion of said blade sheet connecting said multiple blades, and a nose cap for preventing distortion of said web from a true plane thereby to assist in holding said blades in fixed mutual relationship said nose cap terminating in edges occupying said plane and abutting against the surface of said web at said perimeter of the latter closely adjacent said twisted root portions of the blades.

3. In a fan, an air impeller as defined in claim 2, in which the said flat web is perforated to form a circular arrangement of apertures located respectively at the junction of the said root portions of the blades with the said perimeter of said web, together with tangs comprising extensions of the material of the. said nose cap fitting and extending through said apertures respectively and flexed against the surface of the latter in a manner -to hold said nose cap and blade sheet firmly together, each of said tangs being located at a point in the said root portion of each blade which lies circumferentially between the said offsets in the latter.

4. In a fan, an air impeller as defined. in claim 1, in which the said air fanning blades are more than two in number, and the said nose cap is of circular shape, together with means to fasten the said nose cap removably and firmly to the said blade sheet at more than two points spaced around the said perimeter of the said flat web, thereby to prevent substantial departure of said cap from its said circular shape.

5. In a fan, an air impeller as defined in claim 1, in which the said air fanning blades are more than two in number and the said nose cap is of circular shape, together with as many tangs as there are blades each of said tangs forming an extension of the material of saidcap projecting across the said perimeter of the said fiat web and flexed in a manner to hold said nose cap and blade sheet firmly together.

6. In a fan, an air impeller as defined in claim 1, in which there are circumferential spaces between the said root portions of the blades at the periphery of the said flat web, together with tangs forming extensions of the material of said cap registering with said spaces and projecting respectively therethrough and therebeyond, said tangs being bent over said perimeter of said disclike web and against the surface thereof in a manner to fasten said nose cap and said blade sheet firmly together.

'7. In a fan, an air impeller as defined in claim 1, in which there are circumferential spaces between the said root portions of the blades at the said perimeter of the said flat web, together with tangs forming extensions of the material of the said nose cap registering with said spaces and projecting respectively therethrough and therebeyond flexed in a manner to fasten said nose cap and the said blade sheet firmly together, said tangs being wide enough to fil1 the circumferential extent of the said spaces and being bent radially inward against the flat surface of said web.

8. In a fan, an air impeller as defined in claim 1, in which the said flat web is perforated to form a circular arrangement of apertures located respectively at the junction of the said root portions of the blades with the said perimeter of said web, together with tangs comprising extensions of the material of the said nose cap fitting and extending through said apertures respec-' tively and flexed in a manner to hold said nose cap and blade sheet firmly together.

9. A light weight sheet metal fan impeller comprised of assembled parts each cooperating to strengthen the other, including a thin sheet of pliable material having a flat central portion and air fanning blade formations of said material radiating from said portion, means to mount said sheet for rotation in the plane o'ccupied by its said flat central portion, and a nose cap having peripheral walls whose edges abut against the front surface of said flat central blade sheet portion, together with tangs carried by said cap and extending at circumferentially spaced points from said edges thereof past said central blade sheet portion and bent over against the rear surface thereof to hold said cap edges reinforcingly against said central sheet portion thereby to hold the latter flat, each of said air fanning blade formations of said material having a twisted shape producing a forward ofiset radially outside of said nose cap and close thereto in a manner to retain said peripheral wall edges of the cap against outward distortion in a radial direction and each of said air fanning blade formations of said material further being bowed elsewhere in a manner to produce a tapered trough-like shape merging smoothly with its said twisted shape and serving to extend the stifiening effect of said nose cap to portions of the blade formations which are radially distant from said nose cap.

' MARSHALL H. FRISBIE. 

